Selective laser sintering device

ABSTRACT

A selective laser sintering (SLS) device. The SLS device includes a laser forming unit, a support platform and a driving mechanism. The support platform is configured to support a plurality of raw materials for additive manufacturing of an object including a plurality of sections. The laser forming unit is disposed on the support platform and is configured to lay powders on a surface of each section of the object and sinter the powders. The driving mechanism is disposed under the laser forming unit and includes a vertical driving mechanism and a horizontal driving mechanism. The vertical driving mechanism is connected to the laser forming unit and configured to lift the laser forming unit layer by layer. The horizontal driving mechanism is configured to drive the laser forming unit to move in a horizontal direction with respect to the support platform.

CROSS-REFERENCE TO RELAYED APPLICATIONS

Pursuant to 35 U.S.C. § 119 and the Paris Convention Treaty, thisapplication claims foreign priority to Chinese Patent Application No.201910447966.2 filed May 27, 2019, the contents of which, including anyintervening amendments thereto, are incorporated herein by reference.Inquiries from the public to applicants or assignees concerning thisdocument or the related applications should be directed to: MatthiasScholl P.C., Attn.: Dr. Matthias Scholl Esq., 245 First Street, 18thFloor, Cambridge, Mass. 02142.

BACKGROUND

The disclosure relates to the field of additive manufacturing, and moreparticularly to a selective laser sintering (SLS) device formanufacturing complex parts.

Additive manufacturing process builds a three-dimensional object from acomputer-aided design (CAD) model, usually by successively addingmaterial layer by layer, which is also known as additive manufacturing.One of the key advantages of additive manufacturing is the ability toproduce complex shapes or geometries. A prerequisite for producing a 3Dprinted object is a digital 3D model or a CAD file.

Conventionally, the operation platform of the selective laser sinteringdevices for additive manufacturing is relatively small and isinapplicable to large-sized complex parts. The manufacturing of acomplex part conventionally involves a plurality of steps and manualassembly. This increases the probability of structural errors andreduces the precision and manufacturing efficiency.

SUMMARY

The disclosure provides a selective laser sintering (SLS) device formanufacturing a complex object. The SLS device comprises a laser formingunit, a support platform and a driving mechanism.

The support platform is configured to support a plurality of rawmaterials for additive manufacturing of an object comprising a pluralityof sections; the laser forming unit is disposed on the support platformand is configured to lay powders on a surface of each section of theobject and sinter the powders; the driving mechanism is disposed underthe laser forming unit and comprises a vertical driving mechanism and ahorizontal driving mechanism; the vertical driving mechanism isconnected to the laser forming unit and configured to lift the laserforming unit layer by layer according to a height of each section of theobject so that the object is processed in a vertical direction withrespect to the support platform; and the horizontal driving mechanism isconfigured to drive the laser forming unit to move in a horizontaldirection with respect to the support platform so that the laser formingunit moves over the support platform or separates from the supportplatform. The forming parts are kept on the support platform forsubsequent processes without moving after the completion of SLS forming.

The laser forming unit comprises a housing, two powder cylinders, aseparator, a powder laying unit, a laser unit, and a plurality ofheating units; the powder laying unit is disposed in the housing andcomprises a plurality of powder cylinders and a roller; the plurality ofpowder cylinders is symmetrically disposed on both sides of the supportplatform; the roller is configured to move back and forth between theplurality of powder cylinders and the support platform to bring powdersin the plurality of powder cylinders to the support platform; theseparator is disposed in the housing and divides the housing to a firsthalf and a second half; the lasering unit is disposed in the first half,comprises a laser and an oscillating mirror, and is configured to emit alaser to sinter the powders on the support platform; the plurality ofheating units is disposed in the second half and is configured topreheat the powders on the support platform prior to the sintering ofthe powders.

The support platform comprises a groove to accommodate the powdersbrought from the plurality of powder cylinders; the groove comprises asidewall adapted to move vertically with respect to the supportplatform.

The housing comprises an inner wall and a thermal insulation layerattached to the inner wall.

In another aspect, the disclosure provides a selective laser sinteringsystem comprising the aforesaid selective laser sintering device, apowder cleaning device, and a curing-carbonization device. Thehorizontal driving mechanism of the device comprises two guide railsdisposed on both sides of the support platform; the selective lasersintering device, the powder cleaning device, and thecuring-carbonization device each comprises a plurality of pulleysadapted to slide on the guide rails. Each device in turn carries outselective laser sintering, powder cleaning, post-curing andcarbonization processes for the parts to be formed on the supportplatform.

The powder cleaning device comprises a chamber, a rotating rail, an airoutlet, and an air inlet; the rotating rail, the air outlet, and the airinlet are disposed in the chamber; and the air outlet and the air inletare disposed on the rotating rail.

The curing-carbonization device comprises a sealed chamber, an intakepipe, an exhaust pipe, and a heating mechanism disposed in the sealedchamber; and the intake pipe and the exhaust pipe are disposed on theseal chamber.

According to another aspect of the disclosure, also provided is a methodfor forming a SiC ceramic object using the aforesaid system, the methodcomprising:

-   -   1) building a 3D model of an object, slicing the 3D model, and        acquiring data of a plurality of section surfaces of the 3D        model; employing a resin or a resin composite material as a raw        material; placing the raw material in the selective laser        sintering which comprises a housing, a separator, a powder        laying unit, a lasering unit, and a plurality of heating units;        according to the data of a plurality of section surfaces of the        3D model, laying, by the powder laying unit, powders on the        support platform; preheating the powders by the plurality of        heating units; sintering the powders by the lasering unit, to        complete the processing of a first section of the object;        lifting the selective laser sintering, processing a second        section of the object; repeating the lifting and processing, to        yield a green part of the object;    -   2) removing the selective laser sintering device from the        support platform, moving the powder cleaning device on the        support platform, opening the air outlet and the air inlet,        rotating the rotating rail, to remove the powders on the green        part of the object; and the green part is cleaned by rotating        360 degrees; and    -   3) removing the powder cleaning device from the support        platform; moving the curing-carbonization device on the support        platform, the curing-carbonization device comprising a sealed        chamber and a heating mechanism, which is seamlessly connected        with the sealed chamber and the support platform, and heating to        cure the green part of the object by the heating mechanism;        filling the sealed chamber with an inert gas or vacuumizing the        sealed chamber, heating the green part to 600-1500° C. to yield        a carbonized preform of the object, and siliconizing the        carbonized preform to obtain a SiC ceramic object.

In 3), siliconizing the carbonized preform adopts aprecursor-infiltration-pyrolysis (PIP) method, a chemical vaporinfiltration (CVI) method or a reactive infiltration method.

Advantages of the selective laser sintering device according toembodiments of the disclosure are summarized as follows:

1. The SLS device comprises a laser forming unit and a support platform.The support platform is fixedly disposed and the laser forming unit canmove vertically with respect to the support platform. The complex objectis formed layer by layer on the support platform without moving relativeto the support platform, thus reducing the probability of bending,deformation, collapse, or deformation of the object, improving theproduct quality.

2. The selective laser sintering device comprises a housing and aplurality of heating units. The support platform is sealed in thehousing and the raw materials is evenly preheated by the plurality ofheating units prior to forming the object. In addition, through thecoordination of insulation layer and heating unit, the temperaturedistribution in the forming cavity can be uniform, so as to avoid thewarping deformation caused by uneven temperature distribution.

3. The SLS system for manufacturing a SiC ceramic object comprises a SLSdevice, a powder cleaning device, and a curing-carbonization device. Theformation and processing of the object can be achieved in one step,improving the processing efficiency.

4. The method of forming a SiC ceramic object comprises forming a greenpart by SLS, powder cleaning, curing, carbonization, and siliconizing.The method can be used to manufacturing a product with anythree-dimensional structure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a selective laser sintering (SLS)device for manufacturing a complex object according to one embodiment ofthe disclosure;

FIG. 2 is a schematic diagram of a selective laser sintering (SLS)system for manufacturing a complex object according to one embodiment ofthe disclosure;

FIG. 3 is a top view of a powder cleaning device according to oneembodiment of the disclosure;

FIG. 4 is a top view of a curing-carbonization device according to oneembodiment of the disclosure; and

FIG. 5 is a flow diagram of a method of manufacturing a complex objectaccording to one embodiment of the disclosure.

In the drawings, the following reference numbers are used: 1. Selectivelaser sintering device; 2. Powder cleaning device; 3.Curing-carbonization device; 6. Guide rail; 10. Housing; 11. Laser; 12.Oscillating mirror; 13. Thermal insulating layer; 14. Heating unit; 15.Roller; 16. Powder cylinder; 17. Groove; 18. Sidewall; 19. Formed blank;20. Separator; 21. Air outlet; 22. Air inlet; 23. Rotating rail; 24.Door of chamber; 25. Chamber; 30. Sealed chamber; 31. Door of sealedchamber; 32. Sealed layer; 33. Heating mechanism; 34. Intake pipe; 35.Exhaust pipe; 110. Support platform; 111. Lifting mechanism; 112.Vertical driving mechanism; 113. Pulley; 115. Ground.

DETAILED DESCRIPTION

To further illustrate, embodiments detailing a selective laser sinteringdevice for manufacturing a complex object are described below. It shouldbe noted that the following embodiments are intended to describe and notto limit the disclosure.

The disclosure provides a SLS device for manufacturing a large-size andcomplex object, and a SLS system and a method thereof. The SLS systemcomprises a SLS device comprising a support platform, a powder cleaningdevice, and a curing-carbonization device. The support platform isunmovable and the raw materials are processed on the support platform.The SLS device comprises a laser forming unit, a plurality of lasers andoscillating mirrors for producing a blank of an object. The powdercleaning device and the curing-carbonization device can slide on theguide rails of the SLS device to further process the blank of theobject.

FIG. 1 is a schematic diagram of a SLS device for manufacturing alarge-size and complex object according to one embodiment of thedisclosure. As shown in FIG. 1, the SLS device comprises a laser formingunit, a support platform and a driving mechanism; the support platformis a platform for forming an object, the laser forming unit is disposedon the support platform and is configured to lay powder on the sectionsurface of the object and sinter the powders; the driving mechanism isdisposed under the laser forming unit and comprises a vertical drivingmechanism and a horizontal driving mechanism. After the laser formingunit completes a SLS process on one section surface on the supportplatform, the vertical driving mechanism lifts the laser forming unitlayer by layer according to the height of each section of the object sothat the object is processed in a vertical direction with respect to thesupport platform, which avoids up and down movement of the parts due toa moving support platform. And the horizontal driving mechanism isconfigured to drive the laser forming unit to move in a horizontaldirection with respect to the support platform so that the laser formingunit moves over the support platform or separates from the supportplatform, avoiding moving the parts in subsequent processing.

The SLS device comprises a housing 10 and a powder laying unit; thepowder laying unit is disposed in the housing and comprises a pluralityof powder cylinders 16 and a roller 15; the plurality of powdercylinders 16 is symmetrically disposed on the both sides of the supportplatform; the roller 15 moves back and forth between the plurality ofpowder cylinders and the support platform, so that the powder broughtfrom the plurality of powder cylinders 16 is evenly laid on the supportplatform; the housing 10 is internally provided with a separator 20, theinner space of the separator is divided into a first half and a secondhalf; the first half comprises a laser configured to emit a laser sinterthe powder on the support platform. The second half as a forming cavityfor the parts, internally provided with a plurality of uniformlydistributed heating units 14, aiming to preheat the powder on thesupport platform prior to the sintering of the powders.

A plurality of laser units and heating units 14 are disposed in thehousing; the laser unit each comprises a laser 11 and an oscillatingmirror 12. In this embodiment, 3×3 sets of laser units are disposed formanufacturing the parts of about 5 meters; the powder on the supportplatform is preheated by heating units 14 prior to the sintering of thepowders; the heating method may be resistance heating and radiantheating; a thermal insulating layer 13 is deposited in the housing, andthe temperature is evenly distributed in the forming cavity to uniformlypreheat the powder; and the temperature distribution in the formingcavity is evenly distributed to uniformly preheat the powder; theseparator 20 is disposed in the housing and separates the laser unitfrom the forming cavity to prevent the laser from overheating.

The SLS device adopts two methods of powder supply including fallingpowder and laying powder; the plurality of powder cylinders is fixed onthe laser forming unit; the heating is disposed in the plurality ofpowder cylinders and is configured to preheat the powder; the roller isquantitatively lifted along with the SLS device 1 by a vertical drivingmechanism 112 supported on the guide rails, realizing a quantitativerise of the powder bed; the SLS device 1 comprises a plurality of lasersand oscillating mirrors which cooperate to complete a rapid andhigh-quality forming of a large-size object; the SLS device 1 employs alarge amount of data processing software and hardware to plan amulti-laser scanning path; a horizontal driving mechanism is disposedunder the laser forming unit; the horizontal driving mechanism comprisesa guide rail 6 which is disposed under the laser forming unit andcooperates with the pulleys 113; the laser forming unit can be moved toor removed from the support platform by sliding on the guide rail 6.

The support platform comprises a groove 17, and the powder is spreadacross the groove 17; after one section surface is formed, the sidewallof the groove lifts the height of a single section surface, avoiding thepowder spilled from the groove scattering over other area; the formedblank 19 is in the groove 17; the lifting mechanism 111 on the sidewallrises along with the vertical driving mechanism 112 of the laser formingunit.

FIG. 2 is a schematic diagram of a selective laser sintering (SLS)system for manufacturing a complex object according to one embodiment ofthe disclosure. As shown in FIG. 2, the system comprises a SLS device, apowder cleaning device 2, and a curing-carbonization device 3. Thehorizontal driving mechanism of the SLS device comprises two guide rails6 disposed on both sides of the support platform; the guide rails 6 aredisposed on the ground 115; the SLS device 1, the powder cleaning device2 and the curing-carbonization device 3 each comprises a plurality ofpulleys 113 that cooperates with the guide rail 6 to work; the SLSdevice, the powder cleaning device and the curing-carbonization deviceslide on the guide rails 6; and the object on the support platform aresequentially subjected to the powder sintering, powder removal andcuring-carbonization.

FIG. 3 is a top view of a powder cleaning device according to oneembodiment of the disclosure. As shown in FIG. 3, the powder cleaningdevice 2 comprises a chamber 25, and a rotating rail 23, an air outlet21 and an air inlet 22. The air inlet are disposed in the chamber; andthe air outlet and the air inlet are disposed on the rotating rail; whenthe powder cleaning device 2 is moved over the building platform, thebuilding platform is located in the center of the rotating rail of thechamber 25, and the door 24 of the chamber is thus closed; the airoutlet and the air inlet rotate on the rotating rail and cooperate witheach other, to clean the powder covered on the green part by blowing andsuction from 360 degrees.

The powder cleaning device 2 slides via the guide rails 6, which makethe powder cleaning device move to the support platform without movingthe support platform; the powder cleaning device has an powder airoutlet and an powder air inlet, as well as the powder air outlet isopposite to the powder air inlet and both simultaneously work; thepowder blowing and powder suction equipment can be rotated at 360degrees to achieve omnibearing powder blowing and powder suction,improving the quality of cleaning the powder.

FIG. 4 is a top view of a curing-carbonization device according to oneembodiment of the disclosure. As shown in FIG. 4, thecuring-carbonization device 3 comprises a sealed chamber 30 and aheating mechanism 33, and a sealed layer 32 is disposed in the sealedchamber 30 and is configure to seal the parts on the forming table; andthe curing-carbonization device is moved over the building mechanism toclose the door 31 of the sealed chamber; the heating mechanism 33 isdisposed to surround the support platform and is configure to heat andcure the shaped object; an intake pipe 34 and an exhaust pipe 35 isdisposed in the sealed chamber 30, maintaining the vacuum or inert gasin the sealed chamber 30; the intake pipe 34 is configured to dischargethe inert gas, and the exhaust pipe 35 is responsible for vacuuming andexhaust the gas.

The curing-carbonization device 3 slides on the guide rail 6, which makethe curing-carbonization device move to the support platform withoutmoving the support platform; the curing-carbonization device 3 has afront furnace door and a rear furnace door along the direction of theguide rails 6, which realizes the sealed treatment of the object; thecuring-carbonization device 3 is cured by heating, and the heatingmechanism can heat the parts up to 1000° C., and then cure the shapedobject.

FIG. 5 is a flow diagram of a method of manufacturing a complex objectaccording to one embodiment of the disclosure. A method formanufacturing a large-size and complex SiC ceramic object is summarizedas follows:

(1) Selective Laser Sintering

The SLS device slides on the upper surface of the support platform 110via the guide rails 6 and the pulleys 113; the plurality of powdercylinders 16 and the powder distributing roller are fixed on the SLSdevice and are quantitatively lifted along with the SLS device by avertical driving mechanism 112 supported on the guide rails, realizing aquantitative rise of the powder bed; the groove 17 is fixed on the uppersurface of the support platform 110, and the sidewall of the groove issynchronously raised by the lifting mechanism 111 with the rise of thepowder bed; the SLS device comprises a plurality of lasers andoscillating mirrors which cooperate to complete a rapid and high-qualitymanufacturing of a large-size object; the SLS device 1 employs a bigdata processing software and hardware to plan a multi-laser scanningpath.

(2) Powder Removal

The SLS device 1 is removed along the guide rails 6 after sintering thepowder, and the powder cleaning device 2 slides on the upper surface ofthe support platform; the sidewall 18 of the groove 17 moves down underthe control of the lifting mechanism 111; the air outlet 21 and the airinlet 22 are opened, and the guide rails 23 start to rotate to completea 360-degree rotation cleaning.

(3) Curing

Following the powder removal process, the powder cleaning device 2 isremoved via the guide rails 6, and the curing-carbonization device 3slides to the upper surface of the support platform. The furnace door 4of the curing-carbonization device is closed to form a sealedenvironment, and the formed object is heated to cure.

(4) Carbonization

The sealed layer of the curing-carbonization device is sealed afterfinishing the curing; the exhaust pipe 35 is responsible for vacuuming,and an inert gas is introduced from the intake pipe 34; the heatingmechanism heats the parts up to 600-1500° C. in a vacuum or an inert gasatmosphere for manufacturing a large-size and complex carbon preform.

(5) Siliconizing

The carbon preform obtained in (4) is siliconized to yield a large-sizeand complex SiC ceramic object.

Preferably, in 1), the support platform is a square with a side lengthof 1 m to 10 m; the groove is fixed on the upper surface of the supportplatform, and the sidewall of the groove is lifted via the liftingmechanism by a maximum height of 10 m.

Preferably, the SLS device has a maximum lifting height of 10 m by thevertical driving mechanism.

Preferably, the inert gas described in (4) comprises nitrogen and argon;and the temperature for carbonization is 600-1500° C.

Preferably, the siliconizing method described in (4) comprises aprecursor-infiltration-pyrolysis method, a chemical vapor infiltrationmethod, and a reaction melt infiltration method (including liquid andvapor silicon infiltration).

It will be obvious to those skilled in the art that changes andmodifications may be made, and therefore, the aim in the appended claimsis to cover all such changes and modifications.

What is claimed is:
 1. A device, comprising: 1) a laser forming unit; 2)a support platform; and 3) a driving mechanism; wherein: the supportplatform is configured to support a plurality of raw materials foradditive manufacturing of an object comprising a plurality of sections;the laser forming unit is disposed on the support platform and isconfigured to lay powders on a surface of each section of the object andsinter the powders; the driving mechanism is disposed under the laserforming unit and comprises a vertical driving mechanism and a horizontaldriving mechanism; the vertical driving mechanism is connected to thelaser forming unit and configured to lift the laser forming unit layerby layer according to a height of each section of the object so that theobject is processed in a vertical direction with respect to the supportplatform; the horizontal driving mechanism is configured to drive thelaser forming unit to move in a horizontal direction with respect to thesupport platform so that the laser forming unit moves over the supportplatform or separates from the support platform; and the laser formingunit comprises a powder laying unit and a plurality of heating unitsuniformly distributed above the powder laying unit.
 2. The device ofclaim 1, wherein the laser forming unit comprises a housing, aseparator, and a lasering unit; the powder laying unit is disposed inthe housing and comprises a plurality of powder cylinders and a roller;the plurality of powder cylinders is symmetrically disposed on bothsides of the support platform; the roller is configured to move back andforth between the plurality of powder cylinders and the support platformto bring the powders in the plurality of powder cylinders to the supportplatform; the separator is disposed in the housing and divides thehousing to a first half and a second half; the lasering unit is disposedin the first half, comprises a laser and an oscillating mirror, and isconfigured to emit a laser to sinter the powders on the supportplatform; the plurality of heating units is disposed in the second halfand is configured to preheat the powders on the support platform priorto the sintering of the powders.
 3. The device of claim 1, wherein thesupport platform comprises a groove to accommodate the powders broughtfrom a plurality of powder cylinders of the laser forming unit; thegroove comprises a sidewall adapted to move vertically with respect tothe support platforms.
 4. The device of claim 2, wherein the supportplatform comprises a groove to accommodate the powders brought from theplurality of powder cylinders; the groove comprises a sidewall adaptedto move vertically with respect to the support platform.
 5. The deviceof claim 1, wherein a housing of the laser forming unit comprises aninner wall and a thermal insulation layer attached to the inner wall. 6.The device of claim 2, wherein the housing comprises an inner wall and athermal insulation layer attached to the inner wall.
 7. The device ofclaim 3, wherein a housing of the laser forming unit comprises an innerwall and a thermal insulation layer attached to the inner wall.
 8. Thedevice of claim 4, wherein the housing comprises an inner wall and athermal insulation layer attached to the inner wall.
 9. A system,comprising the device of claim 1, a powder cleaning device, and acuring-carbonization device; wherein the horizontal driving mechanism ofthe device comprises two guide rails disposed on both sides of thesupport platform; the device, the powder cleaning device, and thecuring-carbonization device each comprises a plurality of pulleysadapted to slide on the guide rails.
 10. The system of claim 9, whereinthe powder cleaning device comprises a chamber, a rotating rail, an airoutlet, and an air inlet; the rotating rail, the air outlet, and the airinlet are disposed in the chamber; and the air outlet and the air inletare disposed on the rotating rail.
 11. The system of claim 9, whereinthe curing-carbonization device comprises a sealed chamber, an intakepipe, an exhaust pipe, and a heating mechanism disposed in the sealedchamber; and the intake pipe and the exhaust pipe are disposed on theseal chamber.
 12. The system of claim 10, wherein thecuring-carbonization device comprises a sealed chamber, an intake pipe,an exhaust pipe, and a heating mechanism disposed in the sealed chamber;and the intake pipe and the exhaust pipe are disposed on the sealchamber.
 13. A method of forming an object using the system of claim 9,comprising: 1) building a 3D model of an object, slicing the 3D model,and acquiring data of a plurality of section surfaces of the 3D model;employing a resin or a resin composite material as a raw material;placing the raw material in the laser forming unit comprising a housing,a separator, a powder laying unit, a lasering unit, and a plurality ofheating units; according to the data of a plurality of section surfacesof the 3D model, laying, by the powder laying unit, powders on thesupport platform; preheating the powders by the plurality of heatingunits; sintering the powders by the lasering unit, to complete theprocessing of a first section of the object; lifting the laser formingunit, processing a second section of the object; repeating the liftingand processing, to yield a green part of the object; 2) removing the SLSdevice from the support platform, moving the powder cleaning device onthe support platform, opening the air outlet and the air inlet, rotatingthe rotating rail, to remove the powders on the green part of theobject; and 3) removing the powder cleaning device from the supportplatform; moving the curing-carbonization device on the supportplatform, the curing-carbonization device comprising a sealed chamberand a heating mechanism, seamlessly connecting the sealed chamber andthe support platform, and heating to cure the green part of the objectby the heating mechanism; filling the sealed chamber with an inert gasor vacuumizing the sealed chamber, heating the green part to 600-1500°C. to yield a carbonized preform of the object, and siliconizing thecarbonized preform to obtain a SiC ceramic object.
 14. The method ofclaim 13, wherein in 3), siliconizing the carbonized preform adopts aprecursor-infiltration-pyrolysis (PIP) method, a chemical vaporinfiltration (CVI) method or a reactive infiltration method.